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From: pattis@cs.washington.edu (Richard Pattis)
Newsgroups: comp.lang.modula2
Subject: Re: JPI M2 2.00 - PROCEDURE FUNCTIONS & ERROR CHECKING
Summary: How another language (Ada) does it
Message-ID: <12633@june.cs.washington.edu>
Date: 24 Jul 90 19:00:49 GMT
References: <2029.26AAA199@puddle.fidonet.org>
Organization: U of Washington, Computer Science, Seattle
Lines: 19

Just to see how this "problem" is handled elsewhere:  Ada must report a static
semantic error (excuse me, for those of you reading SIGPLAN) if a function
has NO return statement.  It does not have to diagnose whether the function
must execute a return statement.  If the end of a function is reached without
executing a return statement, Ada raises one of its standard exceptions
(PROGRAM_ERROR).  Interestingly enough, that exception can be handled in the
function itself, so we can include a safeguard (although such code is rarely,
if ever used).

FUNCTION F (params) RETURN INTEGER IS
  locals
BEGIN
  some hairy computation that terminates, but may or may not execute
    a return statement
EXCEPTION
  WHEN PROGRAM_ERROR => RETURN 0;
END F;

Rich Pattis